1. Field of the Invention
The present invention relates to a process for producing a structured area of porous silicon on a substrate, in which silicon is etched and structured by the use of light, as well as to a device for producing a structured area of porous silicon on a substrate.
2. The Prior Art
Porous silicon (PS) has a suitable utility in highly developed silicon microelectronics and is readily manufactured at a favorable cost. Thus, PS is a promising material for applications in the field of sensors. Furthermore, due to its electro-luminescence, it is highly suitable for applications in the field of display technology as well. Display technology is very important in that display and control can be integrated on a chip. Porous silicon has applicability both as an actively luminescent material (e.g. for pixels in flat video screens) and also as a passive material (e.g. for application as a filter in color detectors). Thus, simple structuring of PS at favorable cost is of great importance.
A manufacturing process and apparatus are known from the state of the prior art, as well as also a component that can be manufactured by such a process. Until now, the structured areas consisting of porous silicon were produced by means of normal photolithography, using commercially available photolacquer or, for example, silicon nitride. Porous silicon is produced by an electrochemical etching process with the application of a mixture of hydroflouric acid and ethanol. Illumination of the layers leads to an illumination-dependent additional generation of pairs of electron holes both in the substrate and in the already etched porous silicon. The result is that the holes are used for the chemical reaction required for the etching process.
This has the drawback that a number of successive process steps are required. Another drawback is that the photo lacquer or nitride layer has to be stable versus the electrolyte used for the electrochemical manufacture of porous silicon.